Blade ring for radial-flow elastic fluid turbines



Feb. 21, 1950 A. K. JOHANSSON ET AL BLADE RING FOR RADIAL FLOW ELASTIC FLUID TURBINES Filed July 17, 1945 I l \l 1.1 9/10 /0978 Z ZZ LZ I z 1 mm I l l IIk-A Feb. 21, 1950 A. K. JOHANSSON ETAL 9 BLADE RING FOR RADIAL F LOW ELASTIC FLUID TURBINES Filed July 17, 1945 2 Sheets-Sheet 2 I I f Patented Feb. 21, 1950 BLADE RING FOR RADIAL-FLOW ELASTIC FLUID TURBINES Axel Konrad Johansson, Erik David Lindblom, and Hans Ingvar Olof Ohlberger, Finspong,

Sweden Application July 17, 1945, Serial No. 605,527 In Sweden July 5, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires July 5, 1964 1 Claim.

The present invention relates to blade rings for radial flow elastic fluid turbines, and more particularly to blade rings of the type comprising two or more supporting rings in expansible connection with turbine discs to be carried thereby, and blades inserted between said supporting rings.

Several methods are already known in which to produce such blade rings. One method comprises individually stamping the blades out from a section of iron, properly shaping the ends of the stamped blades to allow their insertion into openings of two shroud rings, welding the inserted ends to said shroud rings, giving the shroud rings a dove-tail profile by turning them in a lathe and connecting them to the supporting rings by a rolling operation.

Another well known method of manufacturing the blade rings includes connecting the blades directly to the supporting rings without the aid of shroud rings. According to said other method the blades are provided with a root at each end which roots, if desired, may be shaped to act as distance pieces, whereupon the outermost portions of the roots are shaped as dove-tails and connected at both ends to a supporting ring by a rolling operation.

Both of these methods suffer from drawbacks.

Operation according to the said first-mentioned method requires the use of a weldable material of sufficient strength for the blades.

Though in operating according to the other method finished blade rings may be obtained in cold state, that is to say. without welding or heating, yet it is necessary to bend the material on opposite sides of the dove-tail grooves inwards and cause it by rolling to firmly embrace the dovetail roots of the blades. This rolling operation requires a material for the supporting rings which is particularly well adapted for rolling.

The present invention has for its object to provide a blade ring which may be manufactured without the use of welding and without the need of any deformation by rolling of the material of the supporting rings in contact with the dovetail projections. These circumstances permit manufacturing the supporting rings from the material that is best suited to the purpose from the strength point of View. No compromise in order to satisfy the requirements as to the welding and rolling qualities of the material need be taken into consideration.

The invention is characterized, chiefly, by the fact that the ends of the blades are formed with outwardly projecting hook-shaped portions engaging correspondingly shaped grooves in the supporting rings and sealed in this engagement by means of locking rings bearing against the inside of the blade ends.

The invention permits a reliable mounting of expansibly supported blade rings whereby the action of the centrifugal force on the blade tensile strains are produced at the outermost portion of the fastening due to the tendency of the supporting rings to twist in following the blade roots. The hook-shaped engagement allows this occurrence without hazarding the safe connection between the blade roots and the supporting rings.

In the accompanying drawings, Fig. 1 is a sectional view of a turbine blade assembly including supporting rings and seating and sealing elements.

Fig. 2 is an enlarged sectional view of part of a modified blade ring and the associated blade root, the ring being shown in partly exploded condition.

Figs. 3 and 4 and 6 to 10 are sectional views of further modified blade rings.

Fig. 5 is a diagrammatic view illustrating a manner of securing the blade root in a ring.

Fig. 5a is a sectional view on line A-A of Fig. 5.

Fig. 11 is a diagrammatic reduced scale view illustrating the use of a locking ring in several parts.

With reference to the drawing, the numeral l designates a blade formed with a dove-tail root 2 at each end. Said roots fit in grooves of two supporting rings 3. One supporting ring is connected to a seating ring 4 adapted to be attached as by caulking to a turbine disc, not shown, said connection being effected by means of an expansion ring 5 and an auxiliary ring 6 caused by rolling to clamp bulbs 1 and 8 of the supporting ring 3 and the expansion ring 5, respectively. If desired, rings 6 and 5 may be formed integrally with one another. Ring 6 should be of a more soft and more readily rolled material than that of the supporting rings. The blade I is clamped at each end between the respective supporting ring 3 and a special locking ring 9 bearing against the inside of the supporting ring and the root of the blade in such a way as to secure a rigid and safe fastening of the blade root to the supporting ring. Ring 9 may be undivided all around and made from a soft material, as supposed in Fig. 1, in which case it is pushed axially into the respective supporting ring, whereupon the ridge l U is forced by rolling into engagement with the root of the blade at the same time that the ring as a whole is forced by rolling against the inner cylindrical surface of the supporting ring. The sealing of ring 9 to the supporting ring may be effected in any well-known way, as for instance, by upsetting of material, spot welding or the like.

Ring 9, however, need not be of a soft material, if, as shown in Figs. 2 and 11, it comprises a number of segments, which may be placed inside the supporting ring. As shown in Fig. 11, the ring9 may comprise three segments, by slitting, it at three points, but it may also be slit at a single point only. After the ring segmentsare placed in their proper positions, a suitable sort'of material is caulked into the clearancesiat.thejoints,

as shown at II in Fig. 11. The clearances at thejoints may, if desired, be filled with a welding material, while the ring segments are forced; by any suitable means against the supporting ring.

In Fig. 2 a ring segment 9 is shown prior to itsapplying to the ring 3 and the blade root 2.

Figs. 3 and 4 illustrate locking rings 12 as locked to the supporting rings against axial displacement by means of coengaging flange and slot, as shown at 13 and I l respectively.

In order to obtain a sufiicient pressure at the bearing surtacesbetween thelocking ring, as 15, Fig. 5, and the blade roots an undivided-ring l6, as shown .in'Fig, 5; maybe driven axially into the divided locking ring in order to force-the segments thereofoutwards. In thiscase the bearing surfaces of the two rings are conical.

As-shown inFig. 6, the segments of the looking ring! maybe formed with peripherally extending ridges l8 fit into corresponding slots in ring 3 and blade root 2. The ridges I3v are caused by rolling to fill up the conical slots. By this means theblade .root is forced against the hook. l9 of the supporting ring so as to firmly engage therein. Said coengaging slots and flanges-together with the engagement efiected by means of the hook 19. do also act to withstand the bending moments as produced by the peripheral forces.

Fig. 7 shows a lockingring having a double set of ridges like l8 in ,Fig. 6 fittedintothe supporting ring'3 and the blade root 2', respectively. Here, it is preferred to use a sort ofmaterial for the locking ring which is easily rolled.

Some further modifications-are shownsinFigs. 8, 9 and 10, in all of which the locking rings, being of substantially the same structure, are designated by reference numeral 2:].

InFigs. 8 and Qlockingr-ingsfl ofrectangular cross section are shown.

Fig. 9 shows a supporting ring 3 having two hooks like l9; 7

In Fig. 10 the reference numeral 22 designates a sheet metal ring or the like adapted to: force blade root 2 against thehook I -9-and--lo'cking ring 2! against the conical surface. 235 of the: blade root. Said ring 22 is sealed by'caulking after the blades and the-lockingring: 2| have'been placed inv their proper positionsand serves'to' lock said members to eachother.

In manufacturing blade rings according-tothe invention,theblades may be placed in the supporting rings either' individually or in groups. By means of a' suitable fixing device" for lathe's groups of blades after turning their roots to the profile desired, may be moved to the supporting rings without changing their positions with relation to each other. Another method involves shrinking the supporting rings onto the blade roots while the blades after turning of their roots are still clamped in the fixing device. In order that the ring 9 may press upon the blade roots by a sufficient force, the supporting ring may be heated during the mounting operation to such a temperature as to produce the contact pressure desired, or the locking ring may for the same purpose be cooled during the mounting operation.

The blades may be provided with distance pieces or formed with roots or welded to shroud rings which are then worked with a view to produce the profile desired. Of course, the invention may also be applied to so called drum rings comprising two or more segments. Finally, the blades may befastenedaccording to the inventionat one end only, whereas the-other end may be fastened in any other way.

What'we claim is:

A blade ring, for radialzfiow elastic: fluid turbines comprising,two-supporting rings, at least one of which is expansibly connected to a turbine disc so as tobe carriedthereby, blades inserted between said-supporting rings, said blades having outwardly extending hookashaped end portions for engaging correspondingly shaped grooves in the supporting rings in order. to. hold thev blades against moving" outwardly with relation tothe supporting rings, andslit lockingringsfor-holding; the bladesagains-t moving inwardly with relation to. the supporting rings,- and undivided rings for keeping said slit locking rings in position against the ends of the.- blades; said undivided rings being axially driven into their positions, the bearing surfaces between the lockingrings and said undivided rings beingconical.

' AXEL KONRAD J OHANSSON.

ERIK DAVID .LINDBLOM. HANS. INGVAR OLQF OH-LBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 876,422 Zvonicek Jan. 14,, 1908 902,915- Roth Nov. 3, 1908 927,658 Kembl'e July 13-, 1909 1,061,754 Knape' May 13, 1913 1,063,331 Dake' June 3, 1913 1,313,058 Bonom Aug. 12, 1919 1,562,970 Kasley Nov; 24, I925 669,797 Wiberg- .May 15, 1928 1,966,041. Nelson July 1.0; 1934 2,173,721 McGee .Sept. 19, 1939 FOREIGN PATENTS Number Country Date 319,323 Great Britain Mar. 6, 1930 606,029 Germany Nov. 23, 1934 719.924 France Feb. 12, 1932 

